SPATIAL-RESOLUTION IN RADIOMETRIC ANALYSIS OF ENAMEL LOSS - A PILOT-STUDY

This pilot study was undertaken to determine whether spatial resolutio n affects radiometric analyses aimed at detecting progressive enamel l oss. Four teeth were weighed, attached to a positioning device, and ev aluated with radiography. A 1 mm strip of enamel was removed from each tooth, and the teeth were weighed again and reexamined by radiography . This process was repeated five times until 1/2 mm of dentin was remo ved. The radiographs were digitized twice with 59 and 200 mu m pixels at 8 bits, providing two series of images with the optical densities c onverted into 256 gray levels. Each series of images was adjusted for contrast variation. Regions of interest were drawn on the crowns, and cumulative percent histograms (CPHs) were calculated. Within a series of CPHs enamel reduction resulted in shifts in the CPHs that were dire ctly proportional to the amount of enamel removed. CPH shifts associat ed with the smaller 59 mu m pixels accounted for 68% of the variation in weights caused by enamel reduction, whereas the shifts associated w ith the larger 200 mu m pixels accounted for 50%. The results indicate that pixel size does affect radiometric determinations of enamel redu ction.